Method and device for providing motion picture films with a magnetic sound track



Oct. 22, 1957 H. THIELE 2,810,317

METHOD AND DEVICE FOR PROVIDING MOTION PICTURE FILMS WITH A MAGNETIC ND TRACK Filed Aug. 11, s

wk r

United States Patent METHOD AND DEVICE FOR PROVIDING MOTION FILMS WITH A MAGNETIC SOUND K Heinz Thiele, Kiel-Wik, Germany, assignor to Zeiss Ikon A. G., Stuttgart, Germany Application August 11, 1953, Serial No. 373,485

Claims priority, application Germany February 18, 1953 6 Claims. (Cl. 88-16.2)

The invention relates to a method and device for providing motion picture films with a magnetic sound track.

It has been proposed heretofore to provide motion picture films with a magnetic sound track which replaces or supplements the commonly used photo-audio sound tracks. The application of such sound tracks can be carried out in connection with the production of the filmnamely, prior to its exposure and development. Due to the narrow width of the magnetic sound track, it is also feasible to provide a picture film, which originally was produced without a sound track, after its production, with a sound track, because the area between the perforations and the edge of the film is sufiicient for application of the sound track. Furthermore, it is also possible to provide developed picture films subsequently with sound or speech. The application of the magnetic sound track can, in this case, be effected with the same method and with the use of the same means which are employed in the coating of the film in immediate connection with its manufacture.

The carrying out of such coating methods, however, is limited to certain branches of industry and is accompanied with loss of time.

It is an object of this invention to eliminate the need for such outside assistance, in that the invention provides means for applying a magnetic sound track to a film during the movement of the developed film through a projector. Thereby every film amateur is offered the possibility to provide his own developed picture films subsequently with speech or sound. Suitably, the projector through which the film is moved for application of the magnetic sound track is operated at a speed different from the normal projection speed, preferably a lower speed. The commercial projectors have provisions for such adjustments.

The application of the magnetic sound track may be effected according to any of the known methods, as, for example, by application of a suspension containing the magnetite. Also, bands treated with said magnetite may be pressed or pasted to the edge portion of the film strip in a width corresponding to the sound track.

Another object of the invention is to provide the device required for carrying out the method in the form of an attachment, the equipment of which is adapted to the selected application method. No separate drive means for moving the film is required, and for guiding the film only such means are necessary which directly serve for the application of the magnetic layer. The attachment is preferably inserted between the reel, from which the film is unwound, and the first guide spool in the projector.

The known application methods operate with an additional heating for drying the applied magnetic sound track or for securing the sound track strips pressed or pasted to the film. It is a further object of the invention to utilize for this purpose the heat produced by the light source of the projector and, therefore, according to the invention, the drying space in the attachment is disposed as close to said light source as possible, preferably in the substantially upwards directed stream of hot air.

On the other hand, if magnetite in a suitable suspension is applied to serve as a magnetic sound track, too rapid evaporation of the liquid has to be avoided. Therefore, it is still another object of the invention first to move the film for drying purposes through a special chamber in which the created vapors are concentrated.

The drawing shows an embodiment of the novel device.

The film projector has the common unwinding reel 1' and take-up reel 2. The arrangement for guiding the film includes the prewinding spool 3, the post-winding spool 4, and the advancing drum 5. Other parts of the projector are the lamp house 6, the lens system 7, and the diagrammatically indicated sound device 8. The equipment required for the application of the magnetic sound track is combined into an attachment unit indicated by dotted lines. It contains essentially the supply receptacle 9 and a roll arrangement 10 which permits the formation of the loops required for drying of the film.

The attachment is inserted in the film guide system of the projector between the unwinding reel 1 and the pre winding spool 3, whereby the drying room containing the reel arrangement 10 is disposed above the stream of hot air emitted from the projector.

For the sound track, magnetite as a suspension in a suitable liquid is used. In order to prevent too rapid drying which may harmfully affect the surface of the sound track, the film is first guided through a separate compartment, a so-called moist chamber, which is indicated by the dotted line 11 and in which the vapors are concentrated.

What I claim is:

l. A method of providing a magnetic sound track on a developed picture film, comprising the steps of feeding the film through a motion picture projector having an unwinding wheel and a feed drum, depositing a strip layer of magnetic material along one edge of said film to form a sound track thereon during the passage of said film from the unwinding wheel to the feed drum of said projector, and finally subjecting said coated area and film to heat to dry said layer during the passage of said film along an area above the illuminating source of said projector.

2. A method of providing a magnetic sound track on a developed picture film, comprising steps of feeding the film through a motion picture projector having an unwinding reel and a feed drum, depositing a layer of magnetic material along one edge of said film to form a sound track when the same is subsequently activated, operating said projector at a reduced speed to permit said material to be evenly deposited on said film, and finally passing the film and the deposited material along one edge thereof along an area above the projector and in the path of the heat rays therefrom to dry said magnetic material as it passes to the feed drum.

3. In combination with a motion picture projector having an unwinding reel and a feed drum, a device for providing a magnetic sound track on a developed picture film comprising means for depositing a strip layer of magnetic material along one edge of said film as it passes from the unwinding reel to the feed drum, means for passing the film along an area above the projector after the strip layer has been applied whereby waste heat from the projector will dry the strip layer on said film, and means for guiding film from said device to said feed drum.

4. In combination with a motion picture projector having an unwinding reel and a feed drum for feeding a developed picture film in front of a light source comprising a device for providing a magnetic sound track on a picture film including means for depositing a strip layer of magnetic material to the developed film, a drying chamber, guide means for guiding the film through said chamber after the application of saidstrip layer, and means for guiding said picture strip across an area above the projector in the path of the rising heat waves from said light source.

5. In combination with a motion picture projector having an unwinding reel and a feed drum for feeding a developed picture film in front of a light source, a device for providing a magnetic sound track on said picture film arranged above said projector, means for depositing a strip layer of magnetic material on said film as it passes from the unwinding reel to the feed drum, guide rollers carried by said device and arranged to feed said film along a sinuous pathway, and guide rollers in said device arranged to feed said film along an area above the light source of said projector so that the heat therefrom will dry the magnetic material deposited on the picture film before the same is fed through said projector.

6. In combination with a motion picture projector having an unwinding reel, feed drum and light source for projecting light through a picture strip fed to said projeetor, a device for providing a magnetic sound track on said picture film as it is fed from the unwinding reel to the feeding drum including a container adapted to feed a magnetite suspension in liquid form to the picture film to provide a magnetic sound track thereon, a series of guide rollers for feeding said film beneath said container, certain of said rollers being arranged to guide the coated picture strip through a drying area arranged above the projector and disposed so that the heat waves from the light source will dry said magnetite suspension.

References Cited in the file of this patent UNITED STATES PATENTS 1,653,467 ONeill Dec. 20, 1927 1,883,562 Chipman et a1 Oct. 18, 1932 1,924,758 Sullivan Aug. 29, 1933 2,105,741 Kuhlik Jan. 18, 1938 2,445,827 Hanson July 27, 1948 2,479,869 Rossman Aug. 23, 1949 2,482,672 Kiel Sept. 20, 1949 2,657,932 Beaney Nov. 3, 1953 FOREIGN PATENTS 325,465 Germany Sept. 13, 1920 OTHER REFERENCES Cameras, M., Magnetic Sound for 8-mm. Projection, Journal of Society of Motion Picture Engineers, vol. 49, October 1947, pages 348 to 356. 

